Selective Electrosynthesis of 2,5‐Diformylfuran in a Continuous‐Flow System

Abstract

The gram-scale selective oxidation of biomass-based chemicals, in particular 5-hydroxymethylfurfural (HMF), into value-added 2,5-diformylfuran (DFF) has a high application potential but suffers from high cost, low selectivity, and harsh reaction conditions. Besides, the electrooxidation strategy requires the usage of expensive electrodes and struggles with low selectivity and efficiency, which restricts its further scaled-up application. In this regard, a continuous-flow system was developed through redox mediator I À /I 2 for the efficient synthesis of DFF, which could accelerate the mass transfer of I À (I 2 ) to aqueous (organic) phase and avoid over-oxidation to achieve high selectivity. After the solvent system, iodine concentration, and reaction time were optimized, highly efficient DFF synthesis (selectivity > 99 %) could be achieved in the electrochemical flow system using inexpensive graphite felt (GF) as electrode. Moreover, selective HMF oxidation was paired with the hydrogen evolution reaction with increased efficiency after using insitu-loaded GF-CoS 2 /CoS and GF-Pt electrodes. As a result, the required energy to achieve the gram-scale synthesis of DFF was significantly reduced, demonstrating outstanding potential for large-scale production of the target product.

Accelerating the dissolution kinetics of iodine with a cosolvent for a high-current zinc–iodine flow battery

“…The cosolvent can also be combined together with other strategies, such as the addition of I 2 -complexing halides, to promote the performance of aqueous I 2 ow batteries. 30,31 We also expect the insights to benet the efforts of using the I 2 /I À redox for owelectrochemical synthesis 32 and CO 2 xation. 33 Author contributions…”

Greening the Synthesis of Biorenewable Fuels and Chemicals by Stoichiometric Reagentless Organic Transformations

“…These intermediates are important on their own merit, and their selective production via electrooxidation of HMF has been attempted. The (2,2,6,6-tetramethylpiperidin-1-yl)­oxyl (TEMPO) mediated oxidation of HMF leads to DFF in satisfactory yields using platinum or graphite anode. , In most cases, the cathodic reaction is a hydrogen evolution reaction (HER) by water electrolysis.…”

“…The (2,2,6,6-tetramethylpiperidin-1yl)oxyl (TEMPO) mediated oxidation of HMF leads to DFF in satisfactory yields using platinum or graphite anode. 216,217 In most cases, the cathodic reaction is a hydrogen evolution reaction (HER) by water electrolysis. The electroreduction of FF and HMF form crucial furanic derivatives with applications spanning from biofuels to chemical intermediates to renewable solvents to monomers for biopolymers.…”

Selective Electrochemical Oxidation of p-Xylylene Glycol Coupled with the Hydrogen Evolution Reaction via a Continuous Flow Strategy

“…Pairing the organic oxidation of alcohol with HER in the flow system through the mediator I – /I 3 – could achieve valuable product synthesis and hydrogen production simultaneously at a higher current. − For example, our group reported efficient electro-oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) with >99% selectivity via mediators of I – /I 3 – and 2,2,6,6-tetramethylpiperidoxyl (TEMPO). However, the product yield dramatically decreased without the TEMPO mediator, which increased the cost and complicated the separation process.…”

“…30−32 For example, our group reported efficient electro-oxidation of 5-hydroxymethylfurfural (HMF) to 2,5diformylfuran (DFF) with >99% selectivity via mediators of I − /I 3 − and 2,2,6,6-tetramethylpiperidoxyl (TEMPO). However, the product yield dramatically decreased without the TEMPO mediator, 33 which increased the cost and complicated the separation process.…”